There is known an arrangement for applying a reaction force from an actuator to an accelerator pedal depending on the amount through which the accelerator pedal is operated {for example, Japanese Laid-Open Patent Publication No. 2007-026218 (hereinafter referred to as “JP2007-026218A”)}. According to JP2007-026218A, an accelerator pedal 3 and a servomotor 19 are operatively coupled to each other by a pedal lever 5 and an arm 15. The servomotor 19 has a drive shaft 19b supporting on a distal end thereof a gear 19a that is held in mesh with a gear segment 15b on the pedal lever 5. The servomotor 19 applies a reaction force through the above structure to the accelerator pedal 3 (see Abstract and FIG. 1).
According to Japanese Laid-Open Patent Publication No. 2005-132225 (hereinafter referred to as “JP2005-132225A”), a depressing force changing means which comprises a variable friction plate 7, a fixed shaft 8, and an actuator 9 (e.g., an electromagnetic solenoid) is used to indicate a switchover of driving characteristics to the driver of a vehicle (see Abstract and [0011]). According to JP2005-132225A, furthermore, a one-way clutch 12 is disposed between a rotational shaft 3 to which an accelerator pedal 2 is fixed and the variable friction plate 7 (FIG. 10). When the accelerator pedal 2 is returned, the one-way clutch 12 prevents a frictional force of the variable friction plate 7 from being transmitted to the rotational shaft 3 (see [0038]).